(function(global) {
	'use strict';
	var global = global || {};
	var _Base64 = global.Base64;
	var version = "1.0.0";
	var buffer;
	var b64chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
	var b64tab = function(bin) {
		var t = {};
		for (var i = 0, l = bin.length; i < l; i++) t[bin.charAt(i)] = i;
		return t;
	}(b64chars);
	var fromCharCode = String.fromCharCode;
	var cb_utob = function(c) {
		if (c.length < 2) {
			var cc = c.charCodeAt(0);
			return cc < 0x80 ? c :
				cc < 0x800 ? (fromCharCode(0xc0 | (cc >>> 6)) +
					fromCharCode(0x80 | (cc & 0x3f))) :
				(fromCharCode(0xe0 | ((cc >>> 12) & 0x0f)) +
					fromCharCode(0x80 | ((cc >>> 6) & 0x3f)) +
					fromCharCode(0x80 | (cc & 0x3f)));
		} else {
			var cc = 0x10000 +
				(c.charCodeAt(0) - 0xD800) * 0x400 +
				(c.charCodeAt(1) - 0xDC00);
			return (fromCharCode(0xf0 | ((cc >>> 18) & 0x07)) +
				fromCharCode(0x80 | ((cc >>> 12) & 0x3f)) +
				fromCharCode(0x80 | ((cc >>> 6) & 0x3f)) +
				fromCharCode(0x80 | (cc & 0x3f)));
		}
	};
	var re_utob = /[\uD800-\uDBFF][\uDC00-\uDFFFF]|[^\x00-\x7F]/g;
	var utob = function(u) {
		return u.replace(re_utob, cb_utob);
	};
	var cb_encode = function(ccc) {
		var padlen = [0, 2, 1][ccc.length % 3],
			ord = ccc.charCodeAt(0) << 16 |
			((ccc.length > 1 ? ccc.charCodeAt(1) : 0) << 8) |
			((ccc.length > 2 ? ccc.charCodeAt(2) : 0)),
			chars = [
				b64chars.charAt(ord >>> 18),
				b64chars.charAt((ord >>> 12) & 63),
				padlen >= 2 ? '=' : b64chars.charAt((ord >>> 6) & 63),
				padlen >= 1 ? '=' : b64chars.charAt(ord & 63)
			];
		return chars.join('');
	};
	var btoa = global.btoa ? function(b) {
		return global.btoa(b);
	} : function(b) {
		return b.replace(/[\s\S]{1,3}/g, cb_encode);
	};
	var _encode = buffer ? function(u) {
			return (u.constructor === buffer.constructor ? u : new buffer(u))
				.toString('base64')
		} :
		function(u) { return btoa(utob(u)) };
	var encode = function(u, urisafe) {
		return !urisafe ?
			_encode(String(u)) :
			_encode(String(u)).replace(/[+\/]/g, function(m0) {
				return m0 == '+' ? '-' : '_';
			}).replace(/=/g, '');
	};
	var encodeURI = function(u) { return encode(u, true) };
	var re_btou = new RegExp([
		'[\xC0-\xDF][\x80-\xBF]',
		'[\xE0-\xEF][\x80-\xBF]{2}',
		'[\xF0-\xF7][\x80-\xBF]{3}'
	].join('|'), 'g');
	var cb_btou = function(cccc) {
		switch (cccc.length) {
			case 4:
				var cp = ((0x07 & cccc.charCodeAt(0)) << 18) |
					((0x3f & cccc.charCodeAt(1)) << 12) |
					((0x3f & cccc.charCodeAt(2)) << 6) |
					(0x3f & cccc.charCodeAt(3)),
					offset = cp - 0x10000;
				return (fromCharCode((offset >>> 10) + 0xD800) +
					fromCharCode((offset & 0x3FF) + 0xDC00));
			case 3:
				return fromCharCode(
					((0x0f & cccc.charCodeAt(0)) << 12) |
					((0x3f & cccc.charCodeAt(1)) << 6) |
					(0x3f & cccc.charCodeAt(2))
				);
			default:
				return fromCharCode(
					((0x1f & cccc.charCodeAt(0)) << 6) |
					(0x3f & cccc.charCodeAt(1))
				);
		}
	};
	var btou = function(b) {
		return b.replace(re_btou, cb_btou);
	};
	var cb_decode = function(cccc) {
		var len = cccc.length,
			padlen = len % 4,
			n = (len > 0 ? b64tab[cccc.charAt(0)] << 18 : 0) |
			(len > 1 ? b64tab[cccc.charAt(1)] << 12 : 0) |
			(len > 2 ? b64tab[cccc.charAt(2)] << 6 : 0) |
			(len > 3 ? b64tab[cccc.charAt(3)] : 0),
			chars = [
				fromCharCode(n >>> 16),
				fromCharCode((n >>> 8) & 0xff),
				fromCharCode(n & 0xff)
			];
		chars.length -= [0, 0, 2, 1][padlen];
		return chars.join('');
	};
	var atob = global.atob ? function(a) {
		return global.atob(a);
	} : function(a) {
		return a.replace(/[\s\S]{1,4}/g, cb_decode);
	};
	var _decode = buffer ? function(a) {
			return (a.constructor === buffer.constructor ?
				a : new buffer(a, 'base64')).toString();
		} :
		function(a) { return btou(atob(a)) };
	var decode = function(a) {
		return _decode(
			String(a).replace(/[-_]/g, function(m0) { return m0 == '-' ? '+' : '/' })
			.replace(/[^A-Za-z0-9\+\/]/g, '')
		);
	};
	var noConflict = function() {
		var Base64 = global.Base64;
		global.Base64 = _Base64;
		return Base64;
	};
	global.Base64 = {
		VERSION: version,
		atob: atob,
		btoa: btoa,
		fromBase64: decode,
		toBase64: encode,
		utob: utob,
		encode: encode,
		encodeURI: encodeURI,
		btou: btou,
		decode: decode,
		noConflict: noConflict
	};
	// if ES5 is available, make Base64.extendString() available
	if (typeof Object.defineProperty === 'function') {
		var noEnum = function(v) {
			return { value: v, enumerable: false, writable: true, configurable: true };
		};
		global.Base64.extendString = function() {
			Object.defineProperty(
				String.prototype, 'fromBase64', noEnum(function() {
					return decode(this)
				}));
			Object.defineProperty(
				String.prototype, 'toBase64', noEnum(function(urisafe) {
					return encode(this, urisafe)
				}));
			Object.defineProperty(
				String.prototype, 'toBase64URI', noEnum(function() {
					return encode(this, true)
				}));
		};
	}
	module.exports = global.Base64;
})(this);
